The present invention relates to a building block for making a model, and in particular to a building block arranged to be connected to other similar building blocks to produce a double helix.
A double helix is a known geometrical shape, and is the natural shape for DNA.
According to the present invention, a block includes a first pivotal connection means provided on one side of the block, two fifths of the length of the block from one end, and a second pivotal connection-means provided on the opposite side of the block two fifths of the length of the block from the other end, the first pivotal connection means being arranged to be connected to the second pivotal connection means of a like underlying or overlying block, so that a plurality of said blocks can be connected to form a double helix.
With the blocks according to the present invention, a model of a double helix can be produced which can easily be assembled and disassembled for use as a toy or puzzle, and can be used as a model for DNA for use as a teaching aid.
It is preferred that each end of the block includes a linking means for connecting a plurality of blocks to a flexible member which follows the double helix shape. The linking means ensures that the blocks making up the double helix shape are correctly spaced when connected to the flexible member to give the desired arrangement, and also hold the blocks together. Preferably the linking means comprises a projection projecting from the end of the block. In this case, the linking means preferably includes an enlarged end portion for holding a flexible member to the block. The linking means is preferably rounded so that the linking means may easily be inserted into a hole or space provided on the flexible member to allow an easy snap fit of the blocks to the flexible member, but which will not become separated easily, and therefore will hold the model together.
The flexible member is preferably formed from a pair of twisted ropes, and in this case the linking means can be received in the gaps between adjacent twists of the rope. In this case, the crossover points of the rope are preferably secured, for example by stitching or with pins. This ensures accurate positioning of the blocks, and ensures that the rope does not become untwisted if the blocks become separated from the rope. Alternatively the flexible member may be in the form of a webbing which includes holes for receiving the linking means.
In an alternative example of the present invention, the linking means may be in the form of recesses provided on the ends of the blocks, and in this case the flexible member carries projections which are received by the recesses on the end of the blocks to connect the blocks to the flexible member.
Each of the blocks preferably have a general trapezoidal shape, with the opposed ends of the block being at an acute angle with respect to each other. The angle between the two opposed ends of the block is approximately 72xc2x0, with the angle between each opposed end and the long side being approximately 54xc2x0. Where linking means are provided on the ends of the blocks, these are preferably provided generally normal to the ends of the blocks.
The block is preferably formed in two separable parts which are connectable together by a joining means. This is especially beneficial where the blocks are to represent base pairs of DNA, since each of the parts of the block represent one of the bases of DNA. The separable blocks also allow the complete disassembly and reassembly of the model. Preferably each part of the block is formed of a different colour. The blocks may be manufactured from a variety of materials including wood, metal and plastics.
Where the block is formed of two component parts, the joining means is preferably in the form of a pin on one of the parts which is receivable in a corresponding hole on the other part. This allows for simple connection and disconnection of the body parts. In this case, it is preferred that more than one pin and corresponding hole are provided for connecting two blocks. In this way, rotational movement of the parts with respect to each other is prevented. In this case, each of the parts of the block may include a pin and a hole, or one of the parts may include a plurality of pins, and the other a plurality of corresponding holes.
A clip is advantageously provided to secure the two parts of the block, and prevent them from falling apart.
Where the block is formed of two parts, there are preferably two sorts of block, in which the overall shape of the block is the same, but in which a part from one block cannot be joined to a part from a different block. This may be achieved by a different arrangement of joining means on the components of each type of block. This is advantageous both where the blocks are used as a toy or puzzle as it increases the complexity of assembling the model, and is beneficial where the blocks are used to represent the base pairs of DNA as this ensures that representations only of allowable base pairs can be made.
Advantageously, the first or second pivotal connection means may be a cylindrical spigot, and the other of the pivotal connection means may be a hole having a diameter slightly larger than the spigot and which receives the spigot. Where the blocks are made from two parts which are joined together, the first and/or second pivotal connection means may be produced in two parts, each of the parts of the pivotal connection means being provided on one part of the block, although it is preferred that the joint is offset from the pivotal connection means. This makes the manufacture of the blocks more simple, and gives greater structural rigidity. Advantageously the block is formed in two halves. Only one shaped piece need then be made. This single piece may be made with one hole on the top side and two holes on the edge which joins to the other half of a block. The single piece may then be adapted by insertion of a spigot into the top hole and a spigot into one of the edge holes into a piece suitable to joining to a second piece with a spigot in the other edge hole to form a single block.
Preferably, the blocks can be arranged to form a double helix in which ten blocks are required to form a complete turn.